One or more woven or non-woven wire screens have been used in shaker or vibrating screen apparatus to size material passing through the wire screens. Known woven wire screens typically consist of a plurality of interwoven weft and warp wires forming a plurality of openings for permitting suitably sized material to pass through the screen. The openings can be square or rectangular. Alternatively, the screen can be formed as a long slot screen where the warp wires are maintained in spaced parallel relation by weft wires arranged in groups of three at spaced intervals along the length of the warp wires. It is conventional to coat the weft wires in certain types of woven wires screens with polyurethane blocks where each polyurethane block completely surround a set of three weft wires to protect the weft wires from wear. It is also conventional to use a plurality of polyurethane blocks as the sole means for binding the warp wires, i.e., no weft wires are used. These latter types of screenings (i.e., screenings lacking any weft wires) are referred to herein as non-woven wire screenings. The phrases “wire screening” and “wire screen” as used herein include woven and non-woven wire screenings or screens.
Conventional woven and non-woven wire screens have limited efficiency due to the limited throughput of product through known woven and non-woven wire screens for a given period of time. The preferred forms of the present invention are designed to significantly improve the throughput and thereby significantly improve the efficiency of wire screens.